The breakout etc didn't occur until the 12th so I don't think ignorance is an excuse for any of the active participants.
There's no way for the Niihau Natives to contact anyone.
they have no Phones, Aylmer Robinson was not allowed to go to the island for his weekly visit, and the only other way is a rather risky 10 hour boat ride.
the Out break only happened because the Guards they had set up were slacking off.
Harada and one of the pilots overpowered the only guard who was taking his duties seriously.
If all Five where actually there, then the events from the 12th on probably wouldn't have taken place, or if they did, it would probably end with the pilots and Harada over powered, and possibly killed, and the last pilot under closer watch.
sense Robinson still hasn't shown up, I suppose it would be reasonable for them to still send the Boat out to contact Robinson and the military.
I suppose the easiest way to do things would for the navy to let Aylmer Robinson have his weekly visit to the Island.
the Pilots would have been sent back with him, and presumably some sort of guards, and turned over to the Military.
the peaceful ends would probably decrease the likelihood of the internment camps, although I don't imagine that it would be much of a decrease.